Forklift Pallet Front-Surface Detection Without 3D-LiDAR
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Solution Overview
Problem
Existing pallet detection methods using 3D-LiDAR are costly and prone to accuracy degradation due to sunlight and limited distance and viewing angle measurements, while methods requiring vertical movement of 2D-LiDAR are time-consuming.
Innovation Solution
A pallet detection device that uses a two-dimensional distance measurement device to acquire point cloud data, detect a straight line corresponding to the front surface of the pallet without vertical movement, and determine the pallet's position and orientation using a scoring system to prioritize points closer to the straight line candidate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 3D-LiDAR is used to detect the pallet position and orientation, then the measurement precision is improved, but the cost increases significantly
Solution Approach 1:
The patent replaces expensive 3D-LiDAR with a combination of inexpensive 2D-LiDAR and imaging camera that can achieve the same detection function at lower cost. The system uses multiple 2D sensors to reconstruct 3D information through coordinate transformation, effectively substituting a single expensive sensor with multiple cheaper sensors working together.
2Adaptability or versatility
If 2D-LiDAR is moved in the vertical direction to acquire three-dimensional data, then the measurement capability is improved, but the measurement time increases
Solution Approach 1:
Instead of moving the 2D-LiDAR vertically to capture 3D data, the patent uses multiple 2D-LiDAR sensors arranged at different positions and angles to simultaneously capture the pallet surface. By combining data from multiple fixed sensors and performing coordinate transformations, the system achieves 3D reconstruction without mechanical movement, thereby reducing measurement time.
3Ease of manufacture
If 3D cameras are used to detect the pallet, then the cost is reduced, but the measurement accuracy degrades due to sunlight and limited distance and viewing angle
Solution Approach 1:
The patent introduces an intermediary processing system that combines data from multiple 2D-LiDAR and imaging camera sensors. Through coordinate transformation and data fusion algorithms, the system compensates for the limitations of individual sensors (such as sunlight interference and viewing angle restrictions) to achieve accurate 3D reconstruction and pallet parameter detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and rapid detection of the pallet's position and orientation without the need for expensive 3D-LiDAR or vertical movement of the 2D-LiDAR, improving efficiency and reducing costs.
Implementation Method 1
a two-dimensional distance measurement device to acquire point cloud data
Implementation Method 2
measure a distance from the sensor to an object located in the predetermined space based on reflected light of the laser light reflected by the object
Data Source
Figure 1A~1E
Figure 2A~2B
Figure 3
AI summary
A pallet detection device comprises: a point cloud acquisition unit configured to acquire point cloud data indicating a point cloud measured by a two-dimensional distance measurement device on a depth map; a straight line detection unit configured to detect a straight line corresponding to a front surface of a pallet based on the point cloud in a region presumed to include the front surface of the pallet in the point cloud data; a line segment detection unit configured to detect a line segment indicating the front surface of the pallet based on the straight line; and a position/orientation acquisition unit configured to acquire position and orientation of the pallet based on the line segment. The straight line detection unit acquires one or more straight line candidates as candidates for the straight line, assigns, for each of the one or more straight line candidates, a score to the point cloud so that points in front of the straight line candidate at a specified distance or more are assigned with a score with a constant whose priority in selection is lower than the rest of points, and selects the straight line from the one or more straight line candidates based on a score accumulated value obtained by accumulating the score for the point cloud in the region presumed to include the front surface of the pallet.